Automotive vehicles include a fresh air inlet at the cowling provided between the forward-most part of the windshield and the rearward-most part of the engine hood. A screen is provided in the cowling to allow fresh air in while keeping leaves and other debris out. The fresh air intake is ordinarily provided at the passenger side of the vehicle. A run-off channel is formed along the forward part of the cowling to lead water away from the fresh air inlet and into and through a drain tube which discharges the water outside of the vehicle.
The fresh air inlet conventionally includes a rain-hat on the fresh air inlet opening of the heating, ventilation and air conditioning (HVAC) system and may or may not include a filter. The rain-hat is designed to limit the amount of moisture allowed to enter the air inlet. This moisture is typically in the form of liquid rain water. Rain-hat designs are directed to minimizing or entirely eliminating the entry of moisture into the air inlet. Such designs include the provision of an upright wall that places the inlet opening at a level higher than the run-off channel. This design allows fresh air to enter into the fresh air inlet while directing water away from the air inlet.
This straight forward design is generally effective at allowing fresh air to enter the fresh inlet while keeping out water. There are also aerodynamics which are to be taken into consideration. It is known that the conventional HVAC system experiences pressure drop created by highly non-uniform distribution of incoming air through the inlet, into the blower or across the air filter inlet face. Experimentation has shown that the maximum air velocities are observed on the air filter directly upstream of the cowl fresh air inlet region in designs with the filter in the rain-hat. This increased air velocity allows for the heavier water particles to get carried into the air filter. As the air filter becomes clogged with water, a greater pressure drop is experienced. The higher pressure drop across the conventional rain-hat forces the air blower motor (typically a scroll-type blower motor wheel) to draw more power from the vehicle in order to deliver the required air volume, resulting in electrical charge and fuel economy issues for the vehicle. The higher pressure drop can also result in additional humidity being pulled into the vehicle interior or with liquid water being pull through the filter and into the HVAC possibly causing failure modes.
Efforts have been made in the past to overcome these problems. These efforts are evidenced in, for example, U.S. Pat. No. 7,625,275, issued on Dec. 1, 2009, to Hoke et al. for “Aerodynamic Rain-Hat for Vehicle Air Intake”; U.S. Pat. No. 7,275,985, issued Oct. 2, 2007, to Lewis et al. for “HVAC Protection System for Automotive Vehicles”; U.S. Pat. No. 7,044,848, issued on May 16, 2006, to Wijaya et al. for “Fresh Air Intake for a Vehicle”; U.S. Pat. No. 6,991,531, issued on Jan. 31, 2006, to Wijaya et al. for “Fresh Air Intake for a Vehicle”; U.S. Pat. No. 6,955,593, issued Oct. 18, 2005, to Lewis et al. for “HVAC Protection System for Automotive Vehicles”; U.S. Reissue Pat. No. RE38,157, issued on Jun. 24, 2003, to Schneider for “Automotive Vehicle HVAC Rain-Hat”; U.S. Pat. No. 5,145,457, issued to Tanigaito et al. on Sep. 8, 1992, for “Ventilation Air Intake Structure of Motor Vehicle”; and U.S. Publication No. 2004/0185767, published Sep. 23, 2004, by Schneider for “Filter Housing Assembly for Transportation Vehicles.”
Some of the advancements embodied in these inventions as well as others provide a vertical inlet rain-hat having a forward tilt. However, this approach does not generally allow for uniform air velocity on the air filter inlet face especially if the cowl volume is limited due to typical vehicle package constraints. This increases the pressure drop across the air filter and also allows for carrying heavier water particles into the air filter.
Accordingly, while these efforts represent advancements in the art of rain-hats for vehicle fresh air intakes, there remains room for improvement in this technology.